Hydraulic jack



HYDRAULIC JACK Filed June 22, 1966 C. G. BELONGIA ETAL Oct. 8, 1968 I VNTORIS 67 i6 6. a 5167; Writ??? Mo ,9 r r/vzKst United States Patent3,404,868 1 HYDRAULIC JACK Y Clyde G. 'Belongia, Racine, and HerbertPikoske, Union Grove, Wis., assignors toWalker Manufacturing Company,Racine, Wis., a corporation of Delaware FiledJune 22, 1966, Ser. No.559,599

' 6 Claims. (Cl. 254-93) Our invention relates to hydraulic jacks and,in particular, to a valve arrangement for connecting the pressurecylinder with the tank when the ram has reached the limit of its stroke.

It is an object of our invention to provide a valve arrangement thateliminates the weep hole normally used in hydraulic jacks.

It is another object to provide a valve arrangement that permits the,use of rubber packings instead of the more expensive leather packings.

The above andother'objects of the invention are accomplished by means ofa construction in which a valve member is movably attached to andcarried by the ram and is normally held byoil pressure on a valve seatformedon the bottom endof the ram. When the ram reaches the limit of itstravel, the valve contacts a stop that separates it from its valve seaton the ram to permit oil in the ram cylinder to flow into the tank.

The invention is illustrated in the accompanying drawing inwhich:

FIGURE 1 is a plan view of a jack embodying the invention;

FIGURE 2 is an elevation taken from the right of FIGURE 1;

FIGURE 3 is an enlarged cross section taken primarily on a midplane ofFIGURE 1 but with a portion thereof offset to reveal the pump cylinderand piston; and

FIGURE 4 is a partial cross section taken substantially at right anglesto the section of FIGURE 3 and modified to include various oil passages.

The jack 1 has a base 3 with a boss 5 on which the bottom end 7 of thetank cylinder 9 is seated and welded in a fluid tight joint 11. The topend 13 of the cylinder 9 is closed by a shouldered tank nut 15 which iswelded to it in a fluid tight joint 17. A ram cylinder 19 is coaxialwith tank cylinder 9 and is fixed on the base 5 inside a recess 21. Thetop end 23 of the ram cylinder 19 extends within but is spaced from thewall of an enlarged aperture 25 inthe tank nut 15 so that there isclearance 27 connecting the space 29 above the top end of the cylinder19 with the tank or reservoir chamber 31 surrounding the cylinder.

The ram 35 moves up and down inside the ram cylinder 19. It has anaperture 37 extending downwardly from its top end 39 and in it isfixedly positioned a sleeve 41 that is internally threaded to engage theexternal threads on extension screw 43 that has a cap or head 45 toengage the load to be lifted. Obviously, the overall length of the ramassembly can be varied by screwing the screw 43 up or down in aperture37.

The bottom end 47 of the ram 35 has a frusto-conical shape with ahorizontal face 49 and an annular tapering surface 51 that acts as avalve seat for the frusto-conical top end of a valve member 53 which hasa horizontal face 55 spaced from ram face 49 and an annular taperingvalve surface 57 mating with valve seat 51. The valve 53 is carried bythe ram 35 through the agency of a screw 59 that extends through a hole61 in the valve and threads into a hole 63 in the bottom end of the ram.The valve 53 has an enlarged aperture 65 aligned with hole 61 and seatedagainst the shoulder so formed is a coil spring 67 that acts against thehead of the screw 59 to resiliently urge the valve 53 onto its valveseat 51.

The outer periphery of the valve member 53 has an annular recess 69 inwhich are positioned an O-ring seal 71 and a back-up washer 73.

It will be understood that to use the jack by raising the ram 35 fluidpressure must be applied by suitable means against the bottom face 75 ofthe valve member 53. The seal 71 prevents such pressure from by-passingthe valve 53 and accordingly the ram 35 and attached parts will riseinside the cylinder 19. During this period oil pressure holds the valveon the ram seat 51. When the ram reaches the permitted limit of itstravel, the annular shoulder 77 on the top of the valve 53 engages thebottom face of a stop and ram bearing ring 79 in the tank nut 15. It isseparated by an O-ring seal 81 from an upper ram bearing ring 83 thatpresses against a retainer ring 85 that fits in a groove inside the tanknut 15. This resistance to upward movement of the valve member 51unseats it from valve seat 53 since the ram 35 is not so obstructed. Oilunder pressure can then flow through valve aperture 63, hole 61, thespace between flat faces 55 and 49, past the valve surfaces 57 and 51,and into the space 29 and clearance 27 at the top end of the ramcylinder whereby it is connected with the reservoir 31. As soon as thepressure drops sufficiently the load on the ram and the spring 67 willcause the valve 53 to seat again but continued pumping of oil will againunseat it in the manner just described. This seat-unseat action mayrepeat as long as oil under pressure is furnished to the bottom of theram assembly.

The structure for furnishing oil under pressure to operate the jackforms no part of the invention and may be conventional. Such structureis illustrated in the drawings wherein the hand pump handle 101 operatesthrough a link 103 to reciprocate pump piston 105 in bore 107. The bore107 is connected through passages 109 and 111 to an enlarged passage 113that connects through passage 115 to the bottom of the ram cylinder 19.Oil from the reservoir 31 passes through filter 117 to enter passages119 and 121 which connect with the passages mentioned above whereby oilreaches the pump chamber 107. Suitable spring seated ball check valves123 and 125 prevent mis-flow during pumping and suction strokes. A handoperated release valve 127 is positioned in suitable apertures (notshown) so that upon release turning thereof passage 113 is connectedthrough another passage (not shown) to the bottom of the reservoir 31.

It will now be realized that the invention provides a simple buteffective means to automatically limit the upward travel of the ram andthat this permits the use of highly effective pressure compressed O-ringseals.

Modifications may be made in the structure illustrated without departingfrom the spirit and scope of the invention.

We claim:

1. A hydraulic jack comprising a base, a tank cylinder mounted on thebase, a ram cylinder mounted on the base inside the tank cylinder, thespace between said cylinders comprising a reservoir for oil, a rammovable up and down inside the ram cylinder, a valve seatable on thebottom of the ram and carried thereby and having a pressure face exposedto oil pressure in the ram cylinder,

said valve being movable relative to the ram and urged by pressure toseat on the ram, means for pumping oil from the reservoir to the ramcylinder under pressure, stop means mounted at the top of the tankcylinder and engageable with the valve to unseat it from the ram, andfluid passage means open when said valve is unseated to connect thepressure face of said valve with said reservoir, the bottom of said ramand the top of said valve having engageable annular conical faces actingto prevent flow when engaged through said fluid passage means.

2. A hydraulic jack comprising a base, a tank cylinder mounted on thebase, a ram cylinder mounted on the base inside the tank cylinder, thespace between said cylinders comprising a reservoir for oil, a rammovable up and down inside the ram cylinder, a valve seatable on thebottom of the ram and carried thereby and having a pressure face exposedto oil pressure in the ram cylinder, said valve being movable relativeto the ram and urged by pressure to seat on the ram, means for pumpingoil from the reservoir to the ram cylinder under pressure, stop meansmounted at the top of the tank cylinder and engageable with the valve tounseat it from the ram, and fluid passage means open when said valve isunseated to connect the pressure face of said valve with said reservoir,said valve having a central aperture through it and including a screwextending through said aperture and mounting the valve on the ram and aspring mounted on the screw and urging the valve onto its seat on thebottom of the ram.

3. A jack as set forth in claim 2 wherein the bottom of said ram and thetop of said valve have engageable annular conical faces acting toprevent flow when engaged through said fluid passage means.

4. A jack as set forth in claim 3 including a tank nut mounted at thetop of the tank cylinder, a retainer ring carried by the tank nut, apair of ram bearing rings carried by said tank nut and reacting againstsaid retainer ring, an O-ring seal between said bearing rings andengaging the ram to prevent leakage of oil from the jack, at least oneof said bearing rings providing said stop means, said valve having anexternal annular groove and an O-ring seal seated in said groove andengaging the inside wall of the ram cylinder to prevent oil leakagebetween the valve and ram cylinder.

5. A hydraulic jack comprising a base, a tank cylinder mounted on thebase, a ram cylinder mounted on the base inside the tank cylinder, thespace between said cylinders comprising a reservoir for oil, a rammovable up and down inside the ram cylinder, a valve seatable on 4 thebottom of the ram and carried thereby and having a pressure face exposedto oil pressure in the ram cylinder, said valve being movable relativeto the ram and urged by pressure to seat on the ram, means for pumpingoil from the reservoir to the ram cylinder under pressure, stop meansmounted at the top of the tank cylinder and engageable with the valvetounseat it from the ram, and fluid passage means open when said valveis unseated to connect the pressure face of said valve with saidreservoir, a tank nut mounted at the top of the tank cylinder, aretainer ring carried by the tank nut, a pair of ram bearing ringscarried by said tank nut and reacting against said retainer ring,an-O-ring seal between said bearing rings and engaging the ram toprevent leakage of oil from the jack, at least one of said bearing ringsproviding said stop means, said valve having an external annular grooveand an O-ring seal seated in said groove and engaging the inside wall ofthe ram cylinder to prevent oil leakage between the valve and ramcylinder.

6. A hydraulic jack comprising a base, a tank cylinder mounted on andrigidly secured to the base, a ram cylinder mounted on the base insidethe tank cylinder, the space between said cylinders comprising areservoir for oil, a ram movable up and down inside the ram cylinder,seal means carried by the lower end of the ram to seal it inside the ramcylinder, means for pumping oil from the reservoir to the ram cylinderunder pressure, a tank nut mounted at the top of the tank cylinder andrigidly secured to it, a retainer ring carried by the tank nut, a pairof ram bearing rings carried by said tank nut and reacting against saidretainer ring, an O-ring seal between said bearing rings and engagingthe ram to prevent leakage of. oil from the jack, the top of said ramcylinder extending in but being spaced from the inside of the tank nutand being free floating with respect to the tank nut and tank cylinder.

References Cited UNITED STATES PATENTS 1,244,317 10/1917 Gaffney 60-52 X1,720,434 7/ 1929 Pedersen 60- -52 1,812,577 6/1931 Albertine 60-522,520,426 8/ 1950 Mueller 60--52 FOREIGN PATENTS 122,950 12/ 1946Australia.

OTHELL M. SIMPSON, Primary Examiner.

